I'm about to install Linux on my new Macbook Pro. In order to do this, I need to resize my Mac OSX partition to allow some free space for Linux. I've booted into the Recovery HD and started "Disk Utility." I then repartitioned my hard drive, resizing the Mac partition to 100GB and leaving the rest as free space for Linux to fill.

The problem I'm having is that whenever I go to apply the changes, I see an error that says:

Partition Failed
Partition failed with the error:

Couldn't modify partition map because the filesystem verification failed.

I then verified the disk, it found errors:

Invalid volume file count.
Invalid volume directory count.
Invalid volume free block count.
Volume header needs minor repair.
The volume Macintosh HD was found corrupt and needs to be repaired.

So I repaired it, then verified it, and everything looked fine.

Then I tried the partition again and it failed with:

Partition Failed
Partition failed with the error:

Couldn't unmount disk.

Then, I try to boot into the regular OS and try resizing the partition there.

I'm met with the errors mentioned above. Rinse, repeat, get nowhere, repeat.

What's going on here? This seems crazy.

  • Attempting a clean reinstall now. This is so weird. Commented Dec 22, 2011 at 18:34
  • The "couldn't unmount disk" error could likely have been bypassed by another reboot. Just reboot back into Recovery HD after repairing the drive. On a side note, it's always a good idea to reboot after ensuring you've successfully repaired the partition.
    – user10355
    Commented Dec 22, 2011 at 19:01
  • Reinstall failed and I can't get into the OS now. Time to go to the Apple Store >:[ Commented Dec 22, 2011 at 19:42
  • I understand your frustration when things don't work as they should, but in the future, please avoid rants or snide remarks. Other people that come here looking for help don't benefit from it and it wastes their time having to comb through it all. Thanks.
    – user10355
    Commented Dec 23, 2011 at 1:23
  • I'm sorry that Apple makes it next to impossible to do fairly easy things like setting up a dual-boot machine. I'm sorry for the cynicism, but you'd be hard-pressed to argue that it was unfounded. Lion has really made things so incredibly difficult to install Linux alongside OSX. I've already been to the Apple Store once today, and I'll probably be going tomorrow to have them do a system-restore I should be able to do myself. Commented Dec 23, 2011 at 1:50

2 Answers 2


Lion has a hidden partition which contains recovery information. Shrinking the partition, according to an Apple employee, is not supported. He hooked up my MBP to an external hard drive and wiped and reinstalled Lion in order to fix things.

In more detail, what happens is this: When you try and resize the main partition, it doesn't include the recovery partition. When you hit "Apply Changes," it does a checksum to make sure that nothing's accessing the drive. It then gets started, doing another checksum, and discovers that something's changed, breaking the previous checksum.


When you install Linux with Boot Camp Assistant it has a menu that helps you partition your HDD with ease. Just fire up Boot Camp Assistant, mount your install, and be on your way.

Keep in mind that this only works if your Mac partition uses the entire HDD.

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